I think if we want to get anywhere we should really differentiate different type of damage a weapon can deal and how effective they are against different targets.
Cutting damage is very effective against anything that is lightly armored such as peasants/levies, skirmishers, archers and horses (so that include all pretty much everything kuzhait :p). An unprotected body part being slashed by a large blade in most cases would be quite unpleasant and in most cases result in severe wounds, incapacitation or death, no matter which part cut through. That's mainly why people started to wear armor in ancient warfare.
Piercing damage is more effective against armor, since very few armor (especially in 11th century) could resist a huge force applied to a very small tip. Even for infantry, putting all your weight on your weapon to pierce through someone ought to be some damage especially as the tip of the weapon could go between links, scales or bands of armors. Plate armor would later provide a better solution to deflect those attacks.
The problem being that unless you hit a vital area, or completely pierce through one's body, you probably wouldn't inflict a killing blow with a single attack but could at least stop an enemy in its tracks (no matter if they are a human or a horse)
Crushing damage will break your bones and rupture internal tissue, so of course wearing an armor will dissipate some of the shock, but no matter how good your armor is, you might always get a few bones broken if a sufficiently heavy object hits you. Weapons that are top heavy such as Axes and Maces tend to deal more crushing damage than more balanced weapons such as swords. You can of course always use a western broadsword as club when all else fails, and get some results, but that wouldn't be very efficient. Unless vitals part are hits like the chest or the head, a target is unlikely to die on the spot from a crushing blow, but designated crushing weapon can make short work of shields and heavier targets as their damage should only somewhat be reduced by armor.
Back to glaive, a pointy glaive (not the curved chinese Guan-dao style) will deal all 3 kinds of damage depending on the situation. If you swing it around you ought to deal some crushing damage with the blade although that's not the best way to use it. You will completely cut through unarmored targets and horses, and if you thrust it, you can also get similar results as a sword, except with a longer reach (at the expense of accuracy).
That's why glaives (and the closely related 2 handed swords) main application is as an anti cavalry weapon, they could be used to cut horse's legs as well as dismount the rider, and were less prone to break than spears/pikes. Of course you can still use them against foot soldiers but would be more impractical than a sword at close range, and more impractical than a spear at longer range. It would probably be quite ineffective against armored troops if you swing it around as only the crushing shockwave would be felt, and instead you would need to try to pierce through the armor with them.
In terms of gameplay my conclusion is that :
- Swinging a glaive should be much less effective against armor, but still deadly to horses and unarmored troops.
- Against armored targets, you would need to use thrusting attacks to deal some kind of damage
- The heavier guan dao glaive wielded by Kuzhait cannot be thrusted, but is heavier and should deal more crushing damage when you swing it around, but should not often one shot an armored target.
The same reasoning can be applied to balance other kinds of weapons. Swinging a sword at a fully armored Sturgian axeman should be the less effective way of killing them, you should rather try to stick them with the pointy end, which is admittedly more difficult, and should be more rewarding as well.
(edit : what i call guan dao is the weapon simply named "glaive" in Bannerlord, "hafted blade" in Warband, but my post is about all kind of glaive in bannerlord including those that can be thrusted like menavlion, which is closer to what was called glaive in europe)